Three-dimensional electro-anatomical mapping of premature atrial complexes originating from the right atrial free wall and treatment by radiofrequency ablation in three horses.
Authors: Buschmann Eva, Van Steenkiste Glenn, Bulckens Hannes, Schauvliege Stijn, Decloedt Annelies, van Loon Gunther
Journal: Equine veterinary journal
Summary
# Editorial Summary: Three-Dimensional Electro-Anatomical Mapping and Radiofrequency Ablation for Equine Premature Atrial Complexes Frequent premature atrial complexes (PACs) pose a significant clinical challenge in equine practice, as they can progress to atrial fibrillation or atrial tachycardia whilst remaining difficult to manage pharmacologically. Buschmann and colleagues employed three-dimensional electro-anatomical mapping (3D EAM) using the CARTO 3 system combined with radiofrequency ablation to treat three horses with PACs originating from the right atrial free wall, with isoprenaline or dobutamine administered during general anaesthesia to provoke the ectopic focus and allow precise localisation via Pattern Matching Filtering. Activation mapping successfully identified the focus of PACs at the mid portion of the right atrial free wall in all three cases, confirming this region as a potential arrhythmogenic site; however, outcomes were mixed, with one horse experiencing complete resolution of PACs after 18 radiofrequency applications with no inducibility on dobutamine challenge, whilst a second case demonstrated pacing-induced phrenic nerve stimulation at the ablation target necessitating cessation of the procedure, and the third horse showing unsuccessful ablation. Whilst the small case number and variable success rate limit definitive conclusions, these findings demonstrate that 3D EAM is a valuable diagnostic tool for precisely localising equine atrial ectopy and suggest radiofrequency ablation warrants further investigation as a potentially curative intervention for horses refractory to medical management—though practitioners should remain cognisant of anatomical complications such as phrenic nerve proximity when considering this approach.
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Practical Takeaways
- •For horses with frequent PACs refractory to medical therapy, 3D electro-anatomical mapping can identify the precise ablation target, but success rates remain variable and procedure carries risks of complications such as phrenic nerve injury
- •Radiofrequency ablation shows promise as a potential permanent treatment for PACs in horses, though this remains an advanced referral procedure best performed at specialized cardiac centres
- •Standard 12-lead ECG and vectorcardiography may not accurately localize PAC origin—3D mapping can reveal the true focus differs from non-invasive predictions
Key Findings
- •Three-dimensional electro-anatomical mapping successfully identified the origin of PACs at the mid portion of the right atrial free wall in all three horses despite ECG suggesting different locations
- •Radiofrequency ablation achieved complete elimination of PACs in one horse (18 energy applications) with PACs no longer inducible by dobutamine
- •Anatomical challenges including pacing-induced phrenic nerve stimulation limited successful ablation in two of three cases
- •The right atrial free wall is a possible arrhythmogenic area for PAC origin in horses, though catheter ablation remains technically challenging